The manufacturing of fibrous insulation products involves making insulation fibers and transforming them into insulation products. Mineral fiber insulation material, for example, is produced by first forming mineral fibers from molten mineral material, such as molten glass, rock, slag or basalt. Numerous fiber forming processes, such as a rotary process with a rotating spinner, a spintex process with a series of parallel drums, or a superfine process where primary glass streams are blasted into fibers by the action of jets of hot gases, can be used to form the mineral fibers. Fibrous insulation products are usually held together by a binder material such as urea phenol-formaldehyde. During the manufacturing process the insulation material, with the binder material applied, is passed through an oven where the binder material is dried and then elevated in temperature to cause the binder material to be cured thereby bonding the fibers together where the fibers intersect with each other. Typical binder curing ovens involve upper and lower continuously moving oven chains that are spaced apart a specified distance to define the thickness of the ultimate mineral fiber product. The oven chains are perforated or foraminous and hot air flows through both the oven chains and the insulation material to cure the binder.
In a typical fiber forming process the fibers are deposited from several fiberizing devices to form a wool pack on a perforated or foraminous conveyor, referred to as a forming chain, which is mounted for travel within a forming chamber. The forming chamber has sidewalls and endwalls, and is provided with suction boxes beneath the forming chain to help pull the insulation fibers down onto the forming chain which forms the insulation pack. Because of the high downward flow of air associated with the fiberizing process, a strong suction force is required to draw the mineral fibers onto the forming chain and prevent the fibers from remaining airborne in the air currents within and surrounding the forming chamber. The suction boxes also help evenly distribute the insulation material across the width of the forming chain so that the subsequent insulation products are generally uniform in density and thickness in the width or transverse direction.
The suction forces required to assure that the mineral fibers remain on the forming chain are often so strong that it is difficult for the insulation material to completely expand or spring up to a desirable height after the wool pack travels beyond the suction boxes. Excessive moisture in the pack prevents the pack from expanding to the desired height. It is preferred to have the wool pack to be expanded to a full, unrestrained height that is greater than the spacing between oven chains prior to entering the oven so that the full height of the cured insulation product can be realized. To achieve the desired expansion of the wool pack prior to the pack's entering the curing oven, it is typical for a pack lift blower to be positioned outside the forming area and beneath the forming chain. The pack lift blower directs air upward through the foraminous forming chain to fluff up the pack and assist the fibers in the pack to recover from the compression during the fiber collecting process. Further, the pack lift blower also has the added dividend of providing beneficial lateral or transverse fiber distribution.
A typical pack lift blower involves a supply of pressurized air from a fan or other source. The pressurized air is supplied via a duct to a nozzle that is flared out to change in cross-sectional shape from a supply conduit, such as an 8 inch diameter circular duct, to an elongated slot positioned directly beneath the forming chain and having a length extending across (i.e., transverse to the machine direction) the underside of the forming chain.
A problem with pack lift blowers is that the they become plugged with fibers and binder material that accumulate on the nozzle outlet. Fibers and binder material reach the nozzle by dropping down through the traveling forming chain, by being sprayed by errant binder sprays, by the accumulation of air-borne fibers and binder drops, and possibly even by condensation of binder material. Eventually, the nozzle outlet becomes so plugged with accumulated binder and fibers that the pack lift blower can no longer perform its function of fluffing up the pack. This leads to a reduction in the recovery value of the insulation product when the insulation package is opened after compression packaging, transport and storage. Stopping the fiber glass insulation production line to clean out the nozzle is an unattractive solution because of the lost value of the production time. Accordingly, it would be valuable if there could be developed a system for maintaining the integrity of the opening of the nozzle for the pack lift blower without requiring shutting down the manufacturing equipment.